This invention relates generally to apparatus for use in a fuel vapor recovery system.
A fuel delivery system of an automotive service or filling station normally includes a number of large fuel storage containers (usually located below ground surface level), one or more fuel dispensers installed at the surface, pipes or conduits connecting the storage containers with the dispensers, and a fuel supply pump-motor for pumping fuel through the pipes from the containers to the dispensers. Such a system normally also includes a leak detector and valves connected in the pipes, and a fuel flow meter mounted in the dispenser cabinet. As described in numerous prior art patents, such as the Bergamini U.S. Pat. No. 5,038,838 and the Pope U.S. Pat. No. 5,355,925, the fuel flow meter generates a series of pulses which are proportioned to the quantity of fuel delivered, and a microprocessor computes and displays the total fuel quantity and price.
In recent years, primarily in response to federal and state regulations, vapor recovery systems are being added to the fuel delivery systems as described above. When fuel is pumped from a supply container into a receiving container, fuel vapor in the receiving container is displaced by the fuel, and, in earlier systems, the displaced vapor was allowed to escape into the environment. However, in a typical vapor recovery system, the vapor is pumped from the receiving container to the supply container. As examples, vapor from an underground storage container is pumped into the tank truck, and vapor from an automotive fuel tank is pumped into the underground storage container. The vapor pump is responsive to the volume of fuel being pumped into the receiving container such that substantially all of the displaced fuel vapor is recovered.
It is a general object of the present invention to provide an improved vapor recovery unit for use in a vapor recovery system as described above.